Unsaturated ketones



United States Patent 3,285,962 UNSATURATED KETONES William J. Farrissey,3n, Northford, Conn., assignor, by mesne assignments, to Esso Researchand Engineering Company, Elizabeth, N.J., a corporation of Delaware NoDrawing. Filed Dec. 16, 1963, Ser. No. 330,617 3 Claims. (Cl. 260-586)The present invention is directed to new and useful materials producedfrom the products obtained from the selective air oxidation ofcyclooctadiene. More particularly, the invention is concerned with theunsaturated ketones derived from cyclooctadiene. In its more specificaspects, the present invention is directed to the arrangement of3-keto-1,5-cyclooctadiene to bicyclo(4,2,0)oct-2- en-4-one.

The present invention may be briefly described as the ketones which maybe produced from the products obtained by the selective air oxidation ofcyclooctadiene. It has been found that the oxidation of cyclooctadienewith molecular oxygen at a temperature within the range from about 50 toabout 75 C. produces an oxidation product from which may be separated amixture of 3-hydroperoxyl,5 cyclooctadiene and6-hydroperoxy-1,4-cyclooctadiene. These hydroperoxides,3-hydroperoxyl-1,5-cyclooctadiene and 6-hydroperoxy-1,4-cyclooctadiene,represent the starting materials of the present invention.

It is preferred that the hydroperoxides obtained in the oxidation ofcyclooctadiene be converted to the corresponding ketones by treating thehydroperoxides with a mixture of an acid chloride and a nitrogen base.The process is preferably carried out at a temperature within the rangeof 10 to +10 C. but is kept as cool as possible to prevent a tarryproduct from forming. Acid chlorides, such as propionyl, benzoylchlorides and the like,

may be employed but acetyl chloride is preferred. The preferred nitrogenbase is pyridine, but other nitrogen bases, such as lutidine, collidine,and picoline, may be used. The conversion of the hydroperoxides to thecorresponding ketones produces a mixture of 3-keto-l,5-cyclooctadieneand 6-keto-1,4-cyclooctadiene. The ketone mixture was analyzed, and itwas apparent from the NMR spectrum that these two ketonic materials werepresent.

According to another aspect of the present invention, the ketone mixtureconsisting of 3-keto-1,5-cyclooctadiene, and 6-keto-1,4-cyclooctadicneis heated to a temperature within the range of about 175 to about 200 C.During the heating of the mixture, the 3-keto-1,S-cyclooctadiene isrearranged to the bicyclo(4,2,0)oct-2-en-4-one. The analysis of theketone mixture after being heated shows a marked change in the infraredand NMR spectrum. Again, the analysis shows two unsaturated ketoneswhich are present in the same relative amounts as the two isomericketones obtained in the conversion of the hydroperoxides.

According to the present invention, unsaturated ketones which arevaluable intenmediate chemicals are obtained. As will be pointed outhereinafter, the unsaturated ketones may be precursors for nylon 8 orfor the production of cis-(Z-carboxycyclobutyl) acetic acid.

The present invention is further illustrated by the following exampleswhich are set forth to merely illustrate and not to limit the presentinvention.

Example 1 In a 1-liter flask equipped with condenser, high speedstirrer, oxygen inlet tube and thermal well is placed 200 cc. (176.6 g.,1.63 moles) of cis,cis-1,5-cyclooctadiene and 0.4 g. ofazoisobutyronitri-le. The solution is heated to 60 C. with a constanttemperature bath, and pure oxygen gas is admitted to the system.Oxidation is continued until 4.23 liter (0.19 mole, 11.7%), of oxygenhas been ab- 3,285,962 Patented Nov. 15, 1956 sorbed. Unreacted olefinis removed by vacuum evaporation at 40 C. after which there remains25.52 g. of a thick viscous oil. The oil is separated into ahydroperoxide phase and a peroxide phase by treatment with a petroleumether-benzene mixture. On addition of 204 cc. of petroleum ether and 41cc. of benzene and cooling to 5 C. two layers are formed. The upperlayer is decanted and solvent evaporated from it to yield 12.37 g.(0.088 mole, 4.6%) of hydroperoxide analyzed as3-hydroperoxy-l,S-cyclooctadiene and 6-hydroperoxy-1,4cyclooctadiene.

Example 2 A solution of 21.66 g. of a crude mixture of cyclooctadienehydroperoxides obtained by the air oxidation of cyclooctadiene andconsisting of 3-hydroperoxy-1,5-cyclooctadiene and6-hydroperoxy-1,4-cyclooctadiene in ml. of chloroform is cooled to 0 C.Sixty ml. of pyridine is added rapidly to this solution, and thereafter,8.4 ml. of acetyl chloride in 10 ml. of chloroform is added slowly tothe solution over 2.5 hours. The solution is further stirred for 45minutes at 0 C. and then allowed to warm to room temperature whilestirring for another 2.25 hours. The product is poured in a separatoryfunnel, and the product is Washed free of pyridine with 1 N HCl. Theresidual acid is washed free with water, and the product is dried in asolvent evaporator. A crude product (18.17 g.) is obtained which upondistillation yielded 9.6 ml. of ketones boiling at 6166 C. at 1.9 mm.The ketone product is a mixture of the following two compounds:

Example 3 A portion of the ketone product formed in accordance withExample 2 plus a crystal of hydroquinone is heated under nitrogen for6.5 hours at a temperature between to about 200 C. Upon distillation,there is obtained material having a boiling point of between 61.569.5 C.at 0.9 mm. This material was analyzed by infrared and NMR spectrum andexhibited peaks on the NMR spectrum at 3.27, a doublet at 4.01- whilethe remaining hydrogen residues were centered at 7.0 and 7.97. Thematerial analyzed was found to have the following structure:

Example 4 A sample of the bicyclic ketone produced in the rearrangementof Example 3 in methanol solution is treated with ozone at 35 C. Afterevaporation of the solvent, the ozonide, 0.3 g., is oxidized with 5 ml.of 30% hydrogen peroxide in 25 ml. of 90% formic acid. The solution isheated slowly at reflux for one hour. On evaporation of the solvent, aperoxide-free product is obtained. The product is separated into atoluene insoluble solid fraction and a white solid having a meltingpoint of .105111 C. after two recrystallizations from toluene. The whitesolid was proved to be cis(2-carboxycyclobutyl) acetic acid having thefollowing structural formula:

l-OOOH Example 2 is treated by passing hydrogen through the mixture, themixture being in the presence of platinum at 3 4 room temperature. Theproduct obtained is essentially bicyc1o(4,2,0)0ct-2-en-4-0ne whichcomprises heating 2,6- pure cyclooctanone which may be further treatedin a cyclooctadienone in the presence of hydroquinone to a known mannerfor use in the production of nylon 8. temperature of between about 175to about 200 C.

The nature and objects of the present invention having been completelydescribed and illustrated and the best 5 References Cited by theExaminer mode thereof set forth, what I wish to claim as new and usefuland secure by Letters Patent is:

What is claimed is:

1. The compound, 6-keto-1,4-cyclooctadiene.

2. The compound having the formula: 10

Buchi et al.: J. Am. Chem. Soc., vol. 84, pp. 3104 to 3108 (1962).

Buchi et al.: J. Am. Chem. 500., vol. 82 pp. 4333 to 4337 (1960).

Chapman et al.: I. Am. Chem. Soc, vol. 85 p. 2015 (1963).

LEON ZITVER, Primary Examiner.

15 M. JACOB, Assistant Examiner.

3. The method of rearranging 2,6-cyc1ooctadienone to

1. THE COMPOUND, 6-KETO-1, 4-CYCLOOCTADIENE.
 2. THE COMPOUND HAVING THEFORMULA:
 3. THE METHOD OF REARRANGING 2,6-CYCLOOCTADIENONE TOBICYCLO(4,2,0)OCT-2-EN-4-ONE WHICH COMPRISES HEATING 2,6CYCLOOCTADIENONEIN THE PRESENCE OF HYDROQUINONE TO A TEMPERATURE OF BETWEEN ABOUT 175 TOABOUT 200*C.